Broadband and distance from the exchange.

Whilst I understand, up to a point, why a broadband signal deteriorates as the line gets further away from the exchange, what is not clear though, is seeing as the broadband signal is but a digital data stream, why is it not possible to regenerate this signal at regular points along the line before noise becomes a too significant factor.

I appreciate my question is shrouded in little direct technical knowledge and thus is probably a tad naive, but I would still be interested in the answer.

Thanks in advance.

Edited by audiodud (Mon 02-Jul-12 19:15:06)

xDSL actually uses a number of analogue signals, and is thus prone to the effects of cross talk. As such, boosting/repeating the signal along the length of the line would casue signiificant cross talk to the variety of other data circuits in the same / adjacent cables.

Edited by deleted (Mon 02-Jul-12 19:27:11)

So presumably if you only boosted it to a maximum value that was only the equivalent to what you would find just out of the exchange, it would still cause problems?

Yes, other signals would be weaker and cross talk would have a serious impact.

Many thanks for the explanation. I'm sure if it had been easy, it would have been done.

In reply to a post by audiodud:

why is it not possible to regenerate this signal at regular points along the line

With what devices?

Can you see a load of boosting devices along your phone line to exchange? Who's gonna put them there? At what cost & who's payng?

Not as simple as that!

If you were simply to use a "repeater" to boost the ASDL signal (essentially an amplifier) then the noise would be amplified as well as the ADSL signal as ADSL, as has already been stated, is a collection of tones produced by the modem.

In practice what would be required is a modem to recover the digital data and a DSLAM to generate ADSL again.

This would require a power source at the repeater point (which could be supplied down the line) and somewhere to put it.

Not a particularly scalable solution and expensive for a single line.

Exactly, and think what that would do to latency.
Fibre is being introduced as a much more practical soution (FTTC and FTTP) to this very problem.